Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

PV cells for water heating

  1. Jul 7, 2010 #1


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    I keep thinking of doing something with Solar Power. (Southern UK)
    The easiest, conceptually would be very basic homemade thermal panels but then there's the problem of how to use the hot (warm) water. That involves plumbing and a special hot tank.
    Once you've gone for that, you may as well spend more and get the high performance 'tubes' and it gets really expensive - even when you shop around.

    If you go for the PV solution, then people think in terms of going the whole hog, getting connected to the Grid and selling what you don't use. This seems to be flavour of the month and there are many very sexy looking packages, which are being sold quite hard - so someone's making a lot of money out of them.

    I was thinking about a much simpler (hi tech / lo tech) system, involving PVs on the roof, no fancy plumbing; just a suitable, low voltage, immersion heater in the existing hot tank. At around £1k for 200W, with no regulation or fancy control needed, you're talking about a payback time of less than 10 years (less if you could only get a cheaper source of PV panels), it would sound to me to be very DIY manageable. Can anyone think of any serious snags? I can't think that a 200W heater would ever produce an embarrassing amount of hot water- and it could always be turned off! PVs don't freeze and a few metres of thick cable would be very easy to run. It seems so obvious???
  2. jcsd
  3. Jul 7, 2010 #2
    Sophicentaur,what are PVs?
    I googled and and amongst other things the following came up:
    performance vauxhall show
    persistent vegetative state
    pig veterinary society
    I doubt if it's any of the above.:tongue2:

    Sorry I found it.I should have googled PV cells(photovoltaic)
    Last edited: Jul 7, 2010
  4. Jul 7, 2010 #3
    I think the first thing needed is for you to do some research and do your sums.
    What is the cost per square metre of cell.
    How efficient are the cells and what is the average expected power output.
    What are the installation costs etc.
  5. Jul 7, 2010 #4


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    Installation is about as cheap as it could be. As I said "a few metres of heavy cable". Fitting an extra heating element could involve removing the tank and putting in a suitable flange (soft solder is easy peasy).

    Efficiency is not 'really' relevant as I would be getting 200W (don't care about the area, particularly) or less, depending on the angle of the Sun etc. My 10 year payback time is accurate enough assuming the prices I have seen so far.

    So, I've really done all you say and I'm interested in any personal experience or exta input.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook